P. Deruelle

Objective To study whether the occurrence and type of placental lesions vary according to the time of onset of COVID‐19 in pregnant women. Design Case–control study. Setting Departments of Gynaecology‐Obstetrics and Pathology, Strasbourg University Hospital, France. Population Cases were 49 placentas of women with COVID‐19. Controls were 50 placentas from women who had a past history of molar pregnancy. COVID‐19 placentas were categorised based on whether birth occurred at more or less than 14 days post‐infection. Methods Comparison between case and controls. Main outcome measures Maternal and neonatal outcomes were recorded. Macroscopic and microscopic examination of the placentas was performed. Results The rate of vascular complications was higher in the COVID groups than in the controls (8 [16.3%] versus 1 [2%], p = 0.02). Signs of fetal (22[44.9%] versus 13 [26%], p = 0.05) and maternal (44 [89.8%] versus 36 [72.0%], p = 0.02) vascular malperfusion and signs of inflammation (11 [22.4%] versus 3 [6.0%], p = 0.019) were significantly more common in the COVID‐19 groups than in the control group. Fetal malperfusion lesions (9 [39.1%] versus 13 [50.0%], p = 0.45) and placental inflammation (4 [17.4%] versus 7 [26.9%], p = 0.42) rates were not significantly different between the two COVID‐19 groups. Chronic villitis was significantly more common when the delivery occurred >14 days after infection than in the group that delivered <14 days after infection (7 [26.9%] versus 1 [4.4%], p = 0.05). Conclusions Our study suggests that SARS‐COV‐2 induces placental lesions that evolve after disease recovery, especially with the development of inflammatory lesions, such as chronic villitis.